Three-person groups of males (G1, G2, and G4) and females (G3) resided for 6 to 12 days in a continuously programmed environment. Subjects followed a behavioral program that determined the sequential and contingent relationships within an inventory of activities. During a positive reinforcement day, each work unit completed by a subject incremented a group account that was divided evenly among the 3 participants at the study's conclusion. During a negative reinforcement day, no money was earned, and the group was assigned a work unit criterion to accomplish to avoid a reduction in accumulated earnings. During avoidance days, subjects exhibited aggressive responses, which differed in magnitude among the 4 groups, as determined from several distinct behavioral measures that reflected the overall status of the microsociety. These effects appear to fall within the conceptual and procedural framework that encompasses analyses of by-products of aversive control, and they suggest that similar variables are operative.